Generally, the bubble ink jet printhead ejects ink through a nozzle by using resistor device to boil the ink. During the process for manufacturing the conventional ink jet printhead, some toxic gas is generated and some operational difficulties reduce the yield rate. In addition, the conventional ink jet printhead has a shorter lifetime resulting from the overall structure problem.
In order to understand the conventional process for manufacturing the conventional ink jet printhead, please refer to FIG. 1. A silicon dioxide layer 12 is formed on a silicon substrate 11 by thermal oxidation and a resistor 13 (e.g. tantalum-aluminum alloy) is formed on the silicon dioxide layer 12 through a sputtering process. Thereafter, an aluminum-conducting layer 14 is formed on a portion of the resistor 13 by sputtering process and then a passivation 15 is formed over the conducting layer 12 and the resistor 13, not covered by the conducting layer 14, by plasma enhanced chemical vapor deposition (PECVD). The passivation 15 is a silicon nitride (Si.sub.3 N.sub.4)/silicon carbide (SiC) layer. Finally, an isolator 16 is formed on the passivation 15 and then a nozzle plate 17 is stuck on the isolator 16 by an adhesive agent.
In the conventional process, the resistor 13 is usually made of tantalum-aluminum alloy. Because the tantalum-aluminum alloy is a material with high resistance, a phenomenon of electron migration will be generated when a current passes through the resistor and is accumulated to cause the resistor at a high temperature so that the useful lifetime of the ink jet printhead is reduced. In addition, there are some toxic gas generated during the process for forming the silicon nitride (Si.sub.3 N.sub.4)/silicon carbide (SiC) layer by PECVD. Therefore, an object of the present invention is to provide an improved process for manufacturing the ink jet printhead to avoid the above described defects of the conventional process.